Photoelectrochemical activity of NiWO4/WO3 heterojunction photoanode under visible light irradiation

NiWO4/WO3 heterojunction photoanode was fabricated for the first time to enhance the photoelectrochemical (PEC) performance under visible light irradiation. Such a photoanode was prepared using a simple deposition-annealing method of NiWO4 nanoparticles onto the surface of porous WO3 films. It was found that the NiWO4/WO3 film synthesized with 25 mM Ni(NO3)2 in ethanol exhibited the best PEC performance, which achieved a 70% increase compared with the pure WO3 film under similar conditions. The promising composite photoanode is desired to be employed for water splitting in the PEC cells. The heterojunction structure offers enhanced photoconversion efficiency and increased the density of carriers. This study reveals that introducing NiWO4 into WO3 films could facilitate the separation and restrain the recombination of photo-generated electron-hole pairs and accelerate the electrons transfer. Synthesis details are discussed, with film morphologies and structures characterized by X-ray diffraction, field emission scanning electron microscope, transmission electron microscope and X-ray photoelectron spectroscopy.